Summary of Significant Accounting Policies - Narrative (Details)	12 Months Ended
	Dec. 31, 2017 USD ($) segment	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Accounting Policies [Line Items]
Lease cancellation fees	$ 13,600,000	$ 7,700,000	$ 2,000,000
Deferred revenue	4,100,000	4,100,000
Advertising and marketing expense	7,600,000	9,400,000	8,700,000
Interest costs capitalized	$ 500,000	$ 0	$ 0
Number of reportable segments (segment) | segment	2
Remaining contractual payments under ground lease agreements	$ 61,284,000
Capitalized internal leasing costs	$ 2,600,000
Building and Building Improvements [Member]
Accounting Policies [Line Items]
Useful life	39 years
Corporate Equipment [Member] | Minimum [Member]
Accounting Policies [Line Items]
Useful life	3 years
Corporate Equipment [Member] | Maximum [Member]
Accounting Policies [Line Items]
Useful life	7 years